Have you ever seen good artists do this thing where, between light and shadow, they
put a really vibrant color? It seems to really effectively pop the lighting in a painting!
But what is this? What causes it to happen in real life? But ... hang on a second. When I look at real
life i don't see this happening at all! The color change between light and shadow in nature seems
more abrupt compared to this. So, if this effect isn't realistic ... then what makes it look so nice?
Well, the effect is in fact based on realism! I'll do two quick paintings here. Same subject in both:
a ball that's lit by a distant lamp light. Now, the values in these two paintings are largely the same,
as you can see here - but color-wise, which one appears more natural and pleasing? It's probably
this one, right? This painting demonstrates something called 'light falloff.'
Some quick basics first! A light source doesn't have infinite strength. Its influence fades at a certain distance.
Every light source falls off like this. It's just the distance range of the falloff changes
depending on how strong the light source is. This graph plots a light's intensity vs distance.
When distance is low, the light's intensity is high. And when distance increases enough, the light's
intensity is low. The falloff line, however, is not like this! No, a light's fall off looks more like
a bell curve. Basically, once that intensity starts falling off, its downward trajectory
accelerates exponentially. If you're the science-y type, you'll know that this trajectory follows the
inverse square law, which states that the intensity equals the inverse of the square of distance ... [wah-wah sound effect denoting overly-technical jargon]
Yeah, let's just do a case study. Here's a photograph. Now, candlelight is a relatively
weak light source. We can expect its falloff to happen over a short distance.
Flipping this to grayscale, take a look at how different the value is from the top of
the white page close to the candle, to the bottom of that same white page just a few
inches further away. Both those values represent light, but the falloff affects them significantly!
OK, flipping back to color now, this should remind you of the painting I did earlier - where
the light's colors change too, depending on the distance from the light source. So let's now look
at how color behaves with light falloff. As you may have guessed, color does not fall off like this.
It's not linear. Much like our graph from earlier, the path a color takes is more like a bell curve.
That is, the color tends to get more saturated as the value decreases. But there's another dimension
to it: the hue changes during fall off too! Specifically, as the value drops, the hue moves away from yellow.
The hue thing is pretty easy to remember: just picture Pac-Man.
Except, instead of eating those little white morsels, this pac-man eats colors off the color wheel!
Let's see that again. Pac-man starts with yellow, and devours color down the line in a rage of gluttony!
Back in both of these examples, we can see the light's colors start yellowish,
and then slide into oranges and reds in sync with the value decrease. All right, you might be wondering
what happens if the light source is, say, red? Well, here's a painting that perfectly nails the falloff
of a red light. Here, Pac-man just starts at red instead of yellow and eats his way down the
line from there. But, a critical note about light in general: the light will completely die away before
pac-man reaches the end of the color wheel. In this case, by the time pac-man gets to about this range,
due to the inverse square law, the light is gone and we're now in the shadow family ... which is a
completely different color calculation! I have a video about shadow colors which you can watch
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All right, so here's an actual painting exercise you can try right now
to help you wrap your mind around this stuff. Just imagine you're looking down at a floor or
something and there's a spotlight coming in from just off screen. I'll start by blocking in that
spotlight's falloff both in value and color, and then I'll place some spheres at various distances
from the light source. I'll do this exercise with two different light colors to really get a feel
for the Pac-man thing. Pretty easy here to see the gradient on the floor. Color-wise, the top one is
doing something like this ... and the bottom one is doing something like this. The added difficulty
on these studies though is i also have to track that light falloff on the spheres themselves.
The spheres closer to the light will be a different color and value than the sphere is further away.
Of course, the spheres will follow the exact same color falloff that the floor does ... you just have
the added task of managing all these objects in the frame. So, here's another photographic example
of light falloff: these spotlights following what should now be a very predictable progression.
Now look at these examples. The cause of the light falloff here is something we haven't seen yet!
The falloff is happening on the same vertical plane. So here, the falloff is not due to distance.
In the case of sunset, the sun is slipping under the horizon. As it does, the lower area gets partially
blocked, therefore reducing the sunlight's intensity, and we get the same falloff pattern.
Witnessing this in real life is both ephemeral and beautiful! Okay we gotta rewind this whooollee thing.
Because, at the very beginning of this video, I promised I'd explain what's going on with this cool edge effect.
Drum roll, please! All that is ... is light falloff, executed in a very compressed space.
That's it! I spent the last six-and-a-half minutes just so I could say that sentence! But yeah,
look: it's just light falloff. It's actually quite similar to what we saw here at sunset -
just compress that down by five-hundred percent. So, let's finish up here with another practice painting. This photo of
my backyard shed is a good opportunity to try it out. It's a good candidate because we have so many
light and shadow edges and boundaries to play with. Right now though, I'm whizzing through the
first bit of the painting while I build some of the basic shapes and values that I need in there.
Because what we're talking about here is mostly a color effect, you don't want to go after it too
early in the process. You need to make sure the more fundamental things are in place
before implementing it. In this case: the shapes and values. All right, closing off the reference because
i'm off on my own now - deviating from nature to add this caricatured light falloff effect!
There are several ways you can go about this. Right here I'm just painting it on a single layer.
I'm using a relatively soft brush, and my color choices should be very recognizable to you now.
Starting with a yellow as that's representative of the afternoon sun, in this case, sliding that hue
down to something orangey. And honestly, on this white surface, I might just stop Pac-man there.
Another way you could go about it is make a new layer, and set it to 'overlay' mode. The nice thing
about overlay mode is it interacts with the colors that are already there. So if you're going over the
edge between light and shadow, overlay mode tends to give you a nice mixture on both sides of the fence.
Of course, even with overlay mode, you'll still need to adjust your colors according to
the progression of light falloff. And it's really up to you to decide how many hues that you want
Pac-man to eat through! With this effect, I usually opt for something between two and three hues. That
seems to be enough to satisfy the aesthetic. Be careful: if you cycle through too many hues in
such a small space, it can start looking like a rainbow or something. Now, one thing that really
helps complement this technique is a little bit of special shadow treatment. I'll make another layer
here set, to overlay mode, and with a big textured brush, I'm putting some emphasized reflected light
into the shadows. Now, please watch my 'Shadow Colors' video for a much more in-depth explanation of this,
but the warm sunlight will bounce into the shadows, warming them up. And the hue I'm choosing for that
warm color continues the progression of my light falloff. So let's say my pac-man hues go from yellow to orange.
I will then warm up my shadows to be reddish. Red being the next hue after orange.
Then I'll just fade away that red into the regular shadow colors that I blocked in here at the start.
And here's the final painting! It's a subtle effect to be sure, but it's quite powerful.
And I think you should give it a try! You might really like the results! So, thanks for watching this video -
I hope you learned something! Special thank-you to my patrons for your ongoing, generous support.
Check out www.marcobucciartstore.com for more art lessons. And as usual, I'll see you in another video :)